1. Field of the Invention
This invention relates to a protective device for a circuit interrupter and, more particularly, it pertains to an indexing mechanism for positively indicating the position of an adjustable magnetic trip for changing a trip spring force while maintaining a constant air gap between a magnet and armature of a magnetic sensing device.
2. Description of the Prior Art
In the circuit-interrupting art, compact circuit breakers have evolved that comprise overcurrent protective devices, or trip units, that function in response to such abnormal currents as overcurrents, ground fault currents, and short circuits that occur in an electrical distribution system. Such trip units are disposed in U.S. Pat. Nos. 3,530,414; 3,797,007; 3,808,847; 3,815,064; 3,950,716; 3,950,717; 4,074,218; and 4,313,098. Although these circuit breakers have a greater range for adjusting for specific trip currents between maximum and minimum air gaps between the magnet and the armature of the trip units, there is a need for an adjustable indexing device that provides positive settings at which a predetermined force is established and maintained on the tension spring of an armature.